▎ 摘　　要

Supercapacitors with high energy density and high power density have attracted numerous attentions. Here, we successfully synthesized Ni6MnO8 material by a fast, facile, and cost-effective method, which the area specific capacitance was found to be as high as 1113 mF/cm(2) at a current density of 1 mA/cm(2). Further, the asymmetric supercapacitor was assembled by using Ni6MnO8 as the positive electrode and graphene as the negative electrode with an operation potential from 0 to 1.4V. It exhibited an area specific capacitance of 69.1m F/cm(2) at 0.5 mA/cm(2) and stable cycling performance which presented about 80% capacitance retention after 5000 cycles at 5 mA/cm(2). The energy density of graphene//Ni6MnO8 supercapacitors was calculated to be 18.81 mWh/cm(2) at a power density of 350.1 mW/cm(2) and still remained 5.8 mWh/cm(2) at a power density of 6990.7 mW/cm(2), meaning that the asymmetric supercapacitor combine excellent power density and energy density. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.